solairhp project: first results of summer campaign

L. Gugliermetti, M. Pieve, L. Saraceno, R. Trinchieri

SolairHP Project: First results of summer campaign

Online, November 11th, 2021

IT Workshop for IEA-HPT ExCo Meeting

ENEA is the Italian National Agency for New Technologies, Energy and Sustainable Economic Development

ENEA-IPSE Lab

The IPSE laboratory works on the Process Engineering and Systems for Energy Decarbonization

The lab is part of the ENEA’s Energy Technologies and Renewable Energy Sources Deparment and it is inside the Energy Production, Storage and Use Division.

It is located inside the Research centre of “La Casaccia” in Rome

ROME


SOLAIR-HP

Funding: 1.4 M€ (cofunded)

Partners:

Call: Decr. 30/06/2014 ex art. 10, c 2, lett. b) D.I. 26/01/2000 per RdS 2012-2014

Period: 04/2018 – 03/2022


SOLAIR-HP: objectives

• Air-solar dual source CO2 HP for air-conditioning of buildings and DHW production.

• Photovoltaic Hybrid Solar Panels (PVT) used as thermal exchanger directly connected to refrigerant.

• Six operative modes (cold, heat, DHW and mixed)

• 7÷10 kW of thermal power• GWP = 1

The project is aimed at developing and testing an innovative transcritical CO2 heat pump.The main features are:


SOLAIR-HP: Placement

Placement: ENEA Casaccia - Roma

Auxiliaries:The heat pump is supported by auxiliaries system able to:• Dispose up to 7/10 kW of thermal power (cold/hot), • Cold and Hot tanks (300 and 500 l),• Fine control of mass flow rate by means of

bypasses and pumps inverters.

The Heat Pump is located at the Research Centre of «La Casaccia» in Rome. The system is installed in an open environment to simulate the real operative conditions.


SOLAIR-HP: Schematics

The schematic of the SOLAIR-HP is visible in figure. By using the three-way valves it is possible to switch the operative mode of the heat pump. The system is composed by several components:

• Heat Recovery Exchanger: to increase the superheating of the fluid before the compressor

• Lamination valve: to control the upper system pressures

• PVT exchanger: to improve system efficiency using the sun irradiation

• Air finned coil: alternative to PVT exchanger

• Cold and hot storage tank: for thermal storage purposes

• Inverter controlled compressor: to control the system power and efficiency


SOLAIR-HP: Operations

#1-2 «Winter» Heating with DHW H2O at Tmax 60 °C

#3-4 «Winter with PVT» Heating with DHW H2O at Tmax 60 °C using the PVT

#5 «Summer» Cooling with water at 12-7 °C

#6 «Heating and Cooling» Cold and Hot water Tmax 60 °C and Tmin 7 °C

The heat pump can be operated in 6 different modes depending on what it is wanted to produce.


Modes #1-2: «Winter»

#1-2: «Winter» Heating with DHW H2O at Tmax 60 °C

Heated Water

Compressor

Recovery Air FinnedCoil

Receiver/Separator

Laminationvalve

Hot exchanger

Cycle:

Loop layout:


Modes #3-4 «Winter with PVT»

«Winter with PVT» Heating with DHW H2O at Tmax 60 °C using the PVT

Heated Water

Compressor

Recovery

PVT

Receiver/Separator

Laminationvalve

Hot exchanger

Cycle:

Loop layout:


Mode #5 «Summer»

#5 «Summer» Cooling with water at 12-7 °C

Cycle:

Loop layout:

Cooled waterCompressor

Recovery Air FinnedCoil

Coldexchanger

Receiver/Separator

Laminationvalve


Mode #6 «Heating and Cooling»

#6 «Heating and Cooling» Cold and Hot water Tmax 60 °C and Tmin 7 °C

Cycle:

Loop layout:Heated Water

Cooled water Compressor

Recovery

Coldexchanger

Receiver/Separator

Laminationvalve

Hot exchanger


Results: #5 modePeriod: 24/08/2021 – 01/10/2021 Mode: #5 «Summer»

Environmental temperatures Compressor frequency effectTmin 23,2 °CTmax 32,1 °CTavg 27,5 °C


Results: #5 mode

Energy Efficiency Ratio Vs compressor frequency and fan speed

• The EER depends on fan speed and compressor frequency.

• There are no improvements to increase fan speed after a specific point (depending on the compressor frequency)

• Environmental temperature affects negatively the efficiency

Going under 50% of compressor can damage the heat pump


Results: #5 mode

Energy Efficiency Ratio Vs compressor frequency and fan speed

• At higher compressor frequencies the EER lowers

• The optimal fan speed increases with the compressor frequency

• Environmental temperature affects negatively the efficiency

• The effect of environmental temperature lowers at high compressor frequency

Going over 80% of compressor was not necessary due to the target cooling power of 10 kW


Results: #5 mode

• Data showed at the same environmental temperature

• At higher compressor frequency the EER lowers

• Cooling power rises with the compressor speed with a good regulation

• The ERR reaches its maximum at 80% of fan speed, the air finned coil is oversized

• The cooling power reaches its maximum at 80% of fan speed, the air finned coil is oversized

Total cooling capacity and the ERR at different compressor speeds and fan speed


Results: #5 mode

• The lamination valve can act manually or automatically in cooling mode

• The percentage represents how much the valve is open

• The automatic control works quite well

• With manual control a higher power is possible but with a lower EER

• Closing too much the valve can lead to overtemperatures

Automatic and manual lamination valve control comparison

Data showed at 60% of compressor frequency and 70% of fan speed


Conclusions

Innovative sun-assisted CO2 transcritical heat pump- Eco-friendly refrigerant (GWP = 1)- Max renewable share exploitation- Integration with solar panels

Test on summer mode (conditioning)

DHW and cooling water tests ongoing (mode #6)Winter test will be made during upcoming winter (innovative PVT usage)

EER and its relation with compressor frequency, fan speeds and lamination degrees


Contacts:[email protected]@[email protected]


solairhp project: first results of summer campaign

Documents